Generally, in a saddle-ridden type vehicle such as a motorcycle, a rear cushion unit is provided between a vehicle body frame and a swing arm. The rear cushion unit absorbs impact which is applied to a vehicle body through a rear wheel when the vehicle travels on a road surface having unevenness. The rear cushion unit generally includes a spring and a damper.
The following Patent Document 1 discloses a saddle-ridden type vehicle in which a rear cushion unit is arranged so as to extend in a vertical direction of a vehicle body. As shown in FIG. 2 of the Patent Document 1, an upper end portion of the rear cushion unit is connected to an upper rear side of a crankcase of an engine suspended from a vehicle body frame via a stay and a lower end portion of the rear cushion unit is connected to a lower portion on the front end side of a swing arm via a link mechanism. The upper end portion of the rear cushion unit is located above the swing arm and the lower end portion of the rear cushion unit is located below the swing arm. Further, the whole of the link mechanism is located below the swing arm.
On the other hand, the following Patent Document 2 discloses a saddle-ridden type vehicle in which a rear cushion unit is arranged so as to extend in a longitudinal direction of a vehicle body. As shown in FIG. 3 of the Patent Document 2, a front end portion of the rear cushion unit (rear suspension) is connected to a cross member bridged between a pair of right and left frame members constituting a vehicle body frame and a rear end portion of the rear cushion unit is connected to an upper portion on the front end side of a swing arm via a link mechanism. Further, the whole of the rear cushion unit is located above the swing arm. Further, the link mechanism includes a triangular suspension arm and a bar-shaped tie rod. The suspension arm is located above the swing arm. The tie rod has an upper end portion located above the swing arm and a lower end portion located below the swing arm. The lower end portion of the tie rod is attached to a lower end portion of a swing arm bracket portion which extends downwardly from a pivot shaft support (rocking shaft support) to support a front end portion of the swing arm.
Patent Document 1: Japanese Patent Application Publication No. 2006-347472A
Patent Document 2: Japanese Patent Application Publication No. 2011-79343A
In the saddle-ridden type vehicle disclosed in the Patent Document 1, the lower end portion of the rear cushion unit and the whole of the link mechanism are located below the swing arm. Accordingly, there is a problem that it is difficult to form, below the front end side of the swing arm, a large space for arranging components such as an exhaust chamber.
Further, in the saddle-ridden type vehicle disclosed in the Patent Document 2, the whole of the rear cushion unit, the whole of the suspension arm and the upper end portion of the tie rod are located above the swing arm. Therefore, it can be considered that a large space may be easily formed below the front end side of the swing arm, as compared to the saddle-ridden type vehicle disclosed in the Patent Document 1. However, in the saddle-ridden type vehicle disclosed in the Patent Document 2, the lower end portion of the tie rod is located below the swing arm. Accordingly, there is a problem that utilization of a space below the front end side of the swing arm is restricted by the presence of the lower end portion of the tie rod.
Further, in the saddle-ridden type vehicle disclosed in the Patent Document 2, the lower end portion of the tie rod is attached to the lower end portion of the swing arm bracket portion which extends downwardly from the pivot shaft support (rocking shaft support) to support the front end portion of the swing arm. As a result, for example, when a rear wheel rides over a convex portion formed on a road surface and thus the swing arm moves upward, a load is applied to the lower end portion of the swing arm bracket portion via the tie rod. Therefore, in order to counter this load, the rigidity of the swing arm bracket portion must be increased. For example, the swing arm bracket portion must be made thicker. As a result, there is a problem that the vehicle body frame becomes heavy.